<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - OffscreenCanvas</title>
    <style>
    html, body {
        height: 100%;
        margin: 0;
    }
    #c {
        width: 100%;
        height: 100%;
        display: block;
    }
    #noOffscreenCanvas {
        display: flex;
        width: 100%;
        height: 100%;
        align-items: center;
        justify-content: center;
        background: red;
        color: white;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
    <div id="noOffscreenCanvas" style="display:none;">
      <div>no OffscreenCanvas support</div>
    </div>
  </body>
<script type="module">
function main() { /* eslint consistent-return: 0 */

	const canvas = document.querySelector( '#c' );
	if ( ! canvas.transferControlToOffscreen ) {

		canvas.style.display = 'none';
		document.querySelector( '#noOffscreenCanvas' ).style.display = '';
		return;

	}

	const offscreen = canvas.transferControlToOffscreen();
	const worker = new Worker( 'offscreencanvas-cubes.js', { type: 'module' } );
	worker.postMessage( { type: 'main', canvas: offscreen }, [ offscreen ] );

	function sendSize() {

		worker.postMessage( {
			type: 'size',
			width: canvas.clientWidth,
			height: canvas.clientHeight,
		} );

	}

	window.addEventListener( 'resize', sendSize );
	sendSize();

}

main();

</script>
</html>

